KOS-MOS
Uncharitable Spy
Normally, I'd say PC, but Ubisoft has done some pretty retarded stuff with their DRM, so...
For instance, if their DRM server goes down, you cannot play. If you're playing, you're kicked off.
I only had a problem with this on AC2 but not Brotherhood. And it never kicked me. What it did do was stop saving my gameplay. I always wondered my the autosave icon would never go away sometimes, only to reload the game later on and notice I just wasted the last hour of playtime